Assault Gun is a set of free wargame rules for miniature wargaming WW2 large-scale battles. The game rules are freely downloadable from the Yahoo site: http://games.groups.yahoo.com/group/assault_gun/
In Assault Gun, one unit is typically either an infantry regiment or a battalion, such as tanks. This means that a large, recognizable, action of WW2 can be fought in a day with a manageable number of units.
To download there are also several orders of battle (OOBS) covering units of armies, corps and divisions; and (presently) three full tested scenarios: Wintergewitter (Manstein's attempted relief of Stalingrad), Kasserine Pass and the Battle of Hannut (France 1940).